movemail and comcast.net

[Noname]

I am trying to use emacs to read mail from mail.comcast.net (after the
change-over from attbi.com).  When I try to configure this, I get
the message 
movemail: Error connecting to POP server: Could not connect to POP
server: Invalid argument

My configuration includes

(setenv "MAILHOST" "mail.comcast.net")
(setq rmail-primary-inbox-list '("po:myusername"))
(setq rmail-pop-password-required t)
(setq rmail-pop-password "mypassword")

where myusername and mypassword are replaced with my actual name and
password.

Is there something I'm doing wrong?

Version info: Emacs 20.7 running under Red Hat Linux

Thanks,

Tom Dietterich, Oregon State University